Electric terminal



y 1941. c. A. JAGGER EIIAL 2,249,474

ELECTRIC TERMINAL Filed Oct. 26, 1939 Inventors: Claude A. dagger- George H. Hamm,

by I

air" Attorney.

Patented July 15, 1941 UNITED STATES PATENT OFFICE ELECTRIC TERMINAL Application October 26, 1939, Serial No; 301,405

2 Claims. (Cl. 173-324) Our invention relates to electric terminals, more particularly to detachable and adjustable terminals for edgewise wound resistors, and has for its object a simple, reliable and low cost terminal.

For a more complete understanding of our invention, reference should be had to the accompanying drawing in which Fig. 1 is a front elevation view partly in section of an electric resistor provided with a terminal embodying our invention; Fig. 2 is a side elevation view of Fig. 1; while Fig, 3 is a fragmentary side elevation view showing a modified form of our invention.

Referring to the drawing, we have shown our invention in one form as applied to an edgewise wound helical resistor comprising a supporting core II! made of a suitable refractory, electrically insulating material, such as porcelain, and provided with a series of slots II and 2 on opposite edges to receive the turns of the edgewise wound resistor I3. Preferably, as shown, the resistor is a ribbon made of a suitable electrical resistance material, such as an alloy of nickel, chromium and iron.

In the operation of these resistors, it is desirable to have a terminal for the connection of the resistor in an electric circuit which terminal is adjustable or detachable so that it may be applied to a selected turn to include a larger or smaller amount of the resistor in the controlled circuit as desired. We provide a terminal |4 made of a suitable electrically conducting material, such as steel, which is clamped in place on a selected turn l5 by means of two transversely extending members, shown as screws |6 and Ito, and which may be removed by loosening these screws.

This terminal comprises a main body member I? having an outwardly extending part Ila provided with a clamping screw l8 by means of which an electrical conductor can be secured thereto, and with two clamping projections llb and I10 substantially on opposite sides of the support In and engaging one side of the resistor turn |5. Between the projections I12) and He, the material of the terminal is cut away, its outline being indicated in Fig. 1 by the dotted line I9; so that the lower edge of the terminal extends over and around the upper edge of the support It), the terminal thus having a forked lower end.

Cooperating with these projections Hi) and We are two small clamping members 20 and 2| through which the screws l6 and Mia extend to secure the members to the main body of the terminal. As indicated clearly in Fig. 2, these members 20 and 2| engage the opposite side of the resistor turn l5 and the screws are tightened so as to clamp the resistor turn at points substantially diametrically opposite each other between the members'ZO and 2| and the projections Nb and He. Thus two pairs of clamping projections llb, 20 and He, 2| are provided. The upper end of each of the members 20 and 2| is bent over to form a laterally extending projection having a central narrow portion 22 extending through an-aperture provided for it in the body member l4 and with a shoulder 23 on each side of the projection 22 which engages the body member. These shoulders space the upper end of each of the members 20 and 2| from the body member a distance 24 slightly greater than the thickness of the resistor turn |5 so that when the screws l5 and IE are tightened, the members 20 and 2| are drawn flat against the side of the resistor turn. To accomplish this, the members 20 and 2| are sprung slightly toward the body member by the pressure of the clamping screws engaging the members 20 and 2| intermediate their ends. A rigid mechanical connection and a good electrical connection with the resistor turn at each point is thus assured.

Integral spacing projections 25 and 26 are also provided on the lower ends of the clamping members 20 and 2| respectively. As indicated in Fig. 1, the members 20 and 2| project toward the support into the spaces at each side between the resistor coil and the support, the spacing projections 25 and 26 being bent laterally on the lower ends of these members in a direction parallel with the axis of the resistor coil so as to engage the inner edge of the turn at substantially diametrically opposite points of the turn. These projections thus definitely position the terminal in a direction away from the support and also position the projection Ill) and He on each side at equal distances from the support. It will be observed that the projections 22 on the upper ends of the members 20 and 2| secure the clamping members against turning movement about the screws l5 and I6. Moreover, the screws themselves are situated just above the upper edge of the resistor turn and definitely fix the position of the terminal in the opposite direction, i. e., toward the support In. Thus by loosening the screws l5 and I6 until the projections 25 and 26 slip by the resistor turn, the terminal can be easily removed.

In Fig. 3 we have shown a modified form of our invention in which an auxiliary clamping member 21 is provided which is in engagement with the main terminal part 28. In this case the main terminal part does not have forked projections corresponding to parts 11b and He of Fig. 1, its lower edge being substantially straight across and these projections being formed by the separate part 21 through which the screw 29 on that side extends. The clamping member 30 on each side has substantially the shape of the members 20 and 2| of Fig, 1 although in this form of our invention, these parts 21 are preferably made of a thinner and spring material whereby close contact between these members and each side of the resistor turn is assured. At the top, the members 20 and 21 are each provided with a lateral projection 3! which extends through an aperture provided for it in the member 21 and, as before, through an aperture in the main terminal part 28.

While we have shown a particular embodiment of our invention, it will be understood, of course, that we do not wish to be limited thereto, since many modifications may be made and we, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric terminal for an edge-wound ribbon resistor comprising a body member having a central upstanding portion provided with means for effecting an electric connection therewith, a pair of spaced clamping projections on the lower end of said member for engagement with one side of a turn of a resistor, a separate clamping member for each of said clamping projections, a screw for securing each of said clamping members to its clamping projection to clamp the sides of the resistor turn between them, said screw forming a stop for engagement with the outer edge of the resistor turn thereby to position said terminal inwardly on the resistor turn, a shoulder on the upper end of each of said clamping members engaging said clamping projection and spacing said clamping member from its clamping projection a distance somewhat greater than the thickness of the resistor turn so that when said screw is tightened said clamping member is bent somewhat to draw said clamping member flat against substantially the entire side of the resistor turn lying between said clamping member and said clamping projection, and a laterally extending positioning projection on the lower end of each of said clamping members extending across the inner edge of said turn to position said terminal outwardly on the resistor turn.

2. An electric terminal for an edge-wound ribbon resistor comprising a body member having a central upstanding portion provided with means for effecting an electric connection therewith, a pair of spaced clamping projections on the lower end of said member for engagement with one side of a turn of a resistor, a separate clamping member for each of said clamping projections, a screw for securing each of said clamping members to its clamping projection to clamp the sides of the resistor turn between them, said screw forming a stop for engagement with the outer edge of the resistor turn thereby to position said terminal inwardly on the resistor turn, each of said clamping projections being provided with an aperture at its upper end on the side of said screw opposite the resistor turn, a laterally extending projection on the upper end of each of said clamping members projecting through said aperture thereby to position said clamping member on said clamping projection against turning movement about its screw, a shoulder on the upper end of each of said clamping members engaging said clamping projection and spacing said clamping member from its clamping projection a distance somewhat greater than the thickness of the resistor turn so that when said screw is tightened said clamping member is bent somewhat to draw said clamping member flat against substantially the entire side of the resistor turn lying between said clamping member and said clamping projection, and a laterally extending positioning projection on the lower end of each of said clamping members extending across the inner edge of said turn to position said terminal outwardly on the resistor turn.

CLAUDE A. JAGGER. GEORGE H. HAMM. 

